The invention relates to a thrust washer arrangement for planet gears in a planet gear carrier.
European Application No. 00 54 852 describes a prior art thrust washer design in which the thrust washers are disposed in pairs on both sides of planet gears. Needle bearings on planet gear pins secured in the planet gear carrier provide a bearing support for the planet gears. The peripheries of the thrust washers are provided with recesses for supplying lubricating oil to the needle bearings.
In this prior art thrust washer design, tapered guide surfaces and radial guide channels must be formed on the inner wall portions of the planet gear carrier in order to guide lubricating oil radially outward to recesses on the inner peripheries of the thrust washers. This is shown in FIGS. 5 and 9 of the European patent application.
A disadvantage of the prior art thrust washer is that on account of axial shifting of the helical planet gears under load, the continuous outer peripheries of the two thrust washers are pressed closely against one another in such a way that it is impossible to flush the bearing with lubricating oil. As a result, the desired cooling and lubrication cannot be achieved, at least during operation with thrust loading in one direction. In addition, tapered guide surfaces and radial guide channels on the planet gear carrier demand complicated machining.
Another prior art thrust washer design is shown in German Patent No. 35 02 076. That design has diametrically opposite, sector-shaped recesses of approximately 110.degree. included angle arranged on its outer periphery. These recesses ensure that their apices guide lubricating oil to the needle bearing elements of the planet gears, without the need for tapered guide surfaces or radial guide channels machined for this purpose in the planet gear carrier.